2011 Digital Orthophotography

2011_Coverage.jpg

In 2011, the North Central Texas Council of Governments facilitated the cooperative purchase
of 4-band, 6-inch resolution digital aerial photography (orthos) for over 6,800 square miles of the NCTCOG region, including Collin, Dallas, Denton, Tarrant and Rockwall counties and portions of Kaufman, Johnson, Ellis, Hood,  Parker and Wise counties. 

The contractor for this project was Sanborn.  The orthos were collected in January and February 2011 and are available for purchase via the DFWMaps Marketplace according to the following price schedule.

Georeferenced TIFF images are sold in  3,000' x 2,000' tiles, or 0.215 square miles. Sample images and a shapefile of the tile structure may be downloaded below:

1-Foot Resolution Sample (coming soon)
TIFF orthophotography grid

Specifications

The coverage area for 2011 includes Dallas, Fort Worth, and surrounding urban and rural counties. Two areas of true orthoimagery were produced over the downtown areas of Dallas and Fort Worth.  The flight design achieved a nominal ground-pixel resolution sufficient for developing 6" pixel orthophotography without oversampling. It was also designed with sufficient forward overlap and strip side laps to ensure total project area coverage. The final orthoimagery meet National Map Accuracy Standards (NMAS) 1"=100' scale mapping (RMSE 1.55' x or y).

Altitude of Capture Approx. 5,000'-8,500' above mean terrain
Focal Length 120 mm (4.72")
Imagery Scale Minimum: 1"= 1764' (Photo scale 1:21167) 
Maximum: 1" = 2129' (Photo scale 1:25552) – Main block DFW restricted airspace
Capture Period January 21 - February 28, 2011
Conditions  Leaf off, cloud free, 30 degree minimum sun angle
Forward Overlap 60% (80% for True Ortho areas)
Sidelap 30% (60% for True Ortho areas)
Coordinate System Texas State Plane, North Central Zone
Horizontal Datum NAD 83
Units US Survey Feet
Format TIFF, MrSID


For more information on the 2011 orthophotography project, view the metadata.

For questions about the 2011 digital aerial photography project, contact Shelley Broyles.